The present invention relates to a thin-film magnetic head with an inductive recording head element for recording information onto a magnetic media such as a hard disk, a floppy disk and others, and relates to a manufacturing method of such magnetic head.
An inductive recording head element mainly consists of two magnetic poles and a coil. The magnetic poles are contacted with each other as a yoke at their back-ends. The front edges of the magnetic poles are exposed and face each other through a recording gap at ABS (Air Bearing Surface) side area. The coil is wound on the yoke.
FIGS. 1 and 2 show sectional views seen from ABS side, each illustrating schematic structure of a part of a conventional inductive recording head element.
In FIG. 1, reference numeral 10 denotes a lower magnetic pole, 11 a recording gap, and 12 an upper magnetic pole, respectively. In this inductive recording head element, the upper magnetic pole 12 has the same width WP2 at the side of the recording gap 11 and at the opposite side thereof.
The inductive recording head element with such shaped upper magnetic pole 12 has large magnetic resistance due to spreading of magnetic flux around the poles, and hence its overwrite characteristics is relatively degraded.
In order to improve such degradation, another inductive recording head element with an upper magnetic pole shaped as shown in FIG. 2 has been proposed. In this figure, reference numeral 20 denotes a lower magnetic pole, 21 a recording gap, and 22 an upper magnetic pole, respectively. The width WP2 of the upper magnetic pole 22 becomes gradually large toward the opposite direction from the recording gap side, and therefore, the cross sectional area of the entrance of magnetic flux flowing is expanded causing the overwrite characteristics to improve.
However, the conventional inductive magnetic head shown in FIG. 2 causes a problem of spreading of effective magnetic track width. Recent requirement for ever increasing of data storage density of magnetic media requires more narrower magnetic track width, therefore this problem is very serious.
It is therefore an object of the present invention to provide a thin-film magnetic head which can achieve both of narrower track width and more enhanced overwrite characteristics, and to provide a manufacturing method of such head.
According to the present invention, a thin-film magnetic head has a recording head element that includes a lower magnetic pole, a recording gap, and an upper magnetic pole facing to the lower magnetic pole through the recording gap. The upper magnetic pole has a first width which is constant in a region from a first edge (lower edge) of the upper magnetic pole at the side of the recording gap to a point at a predetermined distance from the first edge, and has a second width at a second edge (upper edge) of the upper magnetic pole at the opposite side of the recording gap. The second width is larger than the first width.
In the shape of the upper magnetic pole seen from ABS direction, the width (second width) of the second edge of the upper magnetic pole at the opposite side of the recording gap is larger than that (first width) of the first edge of the upper magnetic pole. Thus, the cross sectional area of the input of magnetic flux flowing becomes larger and that of the output of magnetic flux flowing becomes smaller. As a result, overwrite characteristics is greatly enhanced. Furthermore, since the upper magnetic pole has a constant width in a region from the first edge to a point at a predetermined distance from the first edge, spreading of effective track width of the magnetic head can be effectively avoided.
It is preferred that the first width of the upper magnetic pole is continuously varied from the point to the second edge.
It is also preferred that, in the shape seen from ABS direction, an edge of the lower magnetic pole at the side of the recording gap has a protruded part facing to the upper magnetic pole, and that the protruded part has a width which is equal to the first width at the first edge of the upper magnetic pole.
It is also preferred that, in the shape seen from ABS direction, an edge of the lower magnetic pole at the side of the recording gap is flat.
Preferably, the above-mentioned predetermined distance is equal to or longer than 1 xcexcm.
Also, preferably, the head further has a reproducing head element with a magnetoresistive effect (MR) element. This reproducing head element is integrally stacked with the recording head element.
According to the present invention, also, a method of manufacturing a thin-film magnetic head includes the steps of depositing a layer for a lower magnetic pole, depositing, on the lower magnetic pole layer, a layer for a recording gap, and forming an inductive coil and an upper magnetic pole on the recording gap layer. The upper magnetic pole is formed to have a first width which is constant in a region from a first edge of the upper magnetic pole at the side of the recording gap to a point at a predetermined distance from the first edge, and to have a second width at a second edge of the upper magnetic pole at the opposite side of the recording gap. The upper magnetic pole is shaped so that the second width is larger than the first width.
It is preferred that the upper magnetic pole is formed so that the first width of the upper magnetic pole is continuously varied from the point to the second edge.
It is also preferred that the above-mentioned predetermined distance is equal to or longer than 1 xcexcm.
It is preferred that the forming step includes the step of forming a shape of the upper magnetic pole in a frame plating process which uses a photo resist, and that this shape is controlled by adjusting exposure condition of the photo resist in an exposure step. The exposure condition may be focus point or numerical aperture (NA) in the exposure step.
It is also preferred that the forming step includes the step of dry etching the lower magnetic pole layer by using the upper magnetic pole as a mask so that an edge of the lower magnetic pole at the side of the recording gap has a protruded part facing to the upper magnetic pole, and that the protruded part has a width which is equal to the first width at the first edge of the upper magnetic pole.
Preferably, the method further includes the step of sequentially depositing on a substrate a first shield layer, a shield gap layer and layers for a magnetoresistive effect element, the step of forming the magnetoresistive effect element, the step of depositing a shield gap layer on the magnetoresistive effect element and the step of depositing the lower magnetic pole layer on the shield gap layer.
Further objects and advantages of the present invention will be apparent from the following description of the preferred embodiments of the invention as illustrated in the accompanying drawings.